Preheat oven to 350F.,Grease and flour a 9 x 13-inch baking pan.,Mix cake mix according to package directions.,______,Reserve remaining batter.,Bake for 20 minutes.,Remove from oven.,Lower oven temperature to 275F.,In a small saucepan, melt caramels, butter, and milk together.,Pour over the baked cake.,Sprinkle semi-sweet chocolate chips and walnuts evenly over caramel.,Pour remaining cake batter evenly over the top of the chocolate chip/walnut/caramel mixture.,Bake at 275F for 20 minutes, then at 350F for 10 minutes.,Cool.,Needs no icing.